1. Field of the Invention
This invention relates to the field of mass air flow sensors and in particular to a production line test apparatus.
2. Prior Art
As part of the normal production process, mass air flow sensors must travel along the production line. In the prior art it was known to test electronics for, first, response time and, second, hot wire temperature set. However, it was not considered to be critical that air flow be controlled during the tests and setting of the parameters. That is, typically air flow was not controlled accurately and there was no measurement of air flow. These are some of the problems this invention overcomes.
During the initial stages of the production process, the mass air flow sensor's electronics module and sensing elements are assembled outside of a cast sensor housing. This initial assembly takes place along a production line on a production mass air flow sensor carrier. The mass air flow sensor electronics module and mass air flow sensor total assembly must be air flow tested at various stations on the production line during this initial assembly. At these air flow test stations, there are production air flow stands that are setting and measuring air flow rates with extreme accuracy. To maintain this level of accuracy, periodic air flow calibrations must take place. It would be desirable to have a calibration carrier for production mass air flow sensor flow stands to accomplish this task. The calibration carrier allows production air flow stands to be calibrated with a high degree of accuracy, while in-process, this minimizing flow stand down time.
During the final stages of the production process, the mass air flow sensor's electronics module and sensing elements are mated to the sensor's housing. This final production process takes place on a production pallet. The mass air flow sensor must be air flow tested at various stations on the production line during this final assembly. At these air flow test stations, production air flow stands set and measure air flow rates with extreme accuracy. To maintain this level of accuracy, periodic air flow calibrations should take place. Such calibrations have typically not been done or have been done by taking the air flow stands off the production line. The calibration is then done in a laboratory. It would be desirable to calibrate production air flow stands with a high degree of accuracy, while in-process, and minimize air flow stand down time. A calibration nozzle set and fixtures for production air flow stands in accordance with an embodiment of this invention accomplish this task.